Text::Xslate::Syntax::TTerse(3pm)

NAME
Text::Xslate::Syntax::TTerse - An alternative syntax compatible with Template Toolkit 2

SYNOPSIS
    use Text::Xslate;
    my $tx = Text::Xslate->new(
        syntax => 'TTerse',
    );

    print $tx->render_string(
        'Hello, [% dialect %] world!',
        { dialect => 'TTerse' }
    );

    # PRE_PROCESS/POST_PROCESS
    $tx = Text::Xslate->new(
        syntax => 'TTerse',
        header => ['header.tt'],
        footer => ['footer.tt'],
    );

DESCRIPTION
TTerse is a subset of the Template-Toolkit 2 (and partially 3) syntax, using "[% ... %]" tags and "%% ..." line code.

Note that TTerse itself has few methods and filters while Template-Toolkit 2 has a lot. See "Text::Xslate::Bridge::*" modules on CPAN which provide extra methods and filters if you want to use those features.

(TODO: I should concentrate on the difference between Template-Toolkit 2 and TTerse)

SYNTAX
This supports a Template-Toolkit compatible syntax, although the details might be different.

Note that lower-cased keywords, which are inspired in Template-Toolkit 3, are also allowed.

  Variable access
Scalar access:

    [%  var %]
    [% $var %]
    [% GET var # 'GET' is optional %]

Field access:

    [% var.0 %]
    [% var.field %]
    [% var.accessor %]
    [% var.$field ]%
    [% var[$field] # TTerse specific %]

Variables may be HASH references, ARRAY references, or objects.

If $var is an object instance, you can call its methods.

    [% $var.method() %]
    [% $var.method(1, 2, 3) %]
    [% $var.method(foo => [1, 2, 3]) %]
    [% $var.method({ foo => 'bar' }) %]

  Expressions
Almost the same as Text::Xslate::Syntax::Kolon, but "infix:<_>" for concatenation is supported for compatibility.

  Loops
    [% FOREACH item IN arrayref %]
        * [% item %]
    [% END %]

Loop iterators are partially supported.

    [% FOREACH item IN arrayref %]
        [%- IF loop.is_first -%]
        <first>
        [%- END -%]
        * [% loop.index %]  # 0 origin
        * [% loop.count     # loop.index + 1 %]
        * [% loop.body      # alias to arrayref %]
        * [% loop.size      # loop.body.size %]
        * [% loop.max_index # loop.size - 1 %]
        * [% loop.peek_next # loop.body[ loop.index + 1 %]
        * [% loop.peek_prev # loop.body[ loop.index - 1 %]
        [%- IF loop.is_last -%]
        <last>
        [%- END -%]
    [% END %]

Unlike Template-Toolkit, "FOREACH" doesn't accept a HASH reference, so you must convert HASH references to ARRAY references by keys(), values(), or kv() methods.

Template-Toolkit compatible names are also supported, but the use of them is discouraged because they are not easy to understand:

    loop.max   # for loop.max_index
    loop.next  # for loop.peek_next
    loop.prev  # for loop.peek_prev
    loop.first # for loop.is_first
    loop.last  # for loop.is_last

Loop control statements, namely "NEXT" and "LAST", are also supported in both "FOR" and "WHILE" loops.

    [% FOR item IN data -%]
        [% LAST IF item == 42 -%]
        ...
    [% END -%]

  Conditional statements
    [% IF logical_expression %]
        Case 1
    [% ELSIF logical_expression %]
        Case 2
    [% ELSE %]
        Case 3
    [% END %]

    [% UNLESS logical_expression %]
        Case 1
    [% ELSE %]
        Case 2
    [% END %]

    [% SWITCH expression %]
    [% CASE case1 %]
        Case 1
    [% CASE case2 %]
        Case 2
    [% CASE DEFAULT %]
        Case 3
    [% END %]

  Functions and filters
    [% var | f %]
    [% f(var)  %]

  Template inclusion
The "INCLUDE" statement is supported.

    [% INCLUDE "file.tt" %]
    [% INCLUDE $var %]

"WITH variables" syntax is also supported, although the "WITH" keyword is optional in Template-Toolkit:

    [% INCLUDE "file.tt" WITH foo = 42, bar = 3.14 %]
    [% INCLUDE "file.tt" WITH
        foo = 42
        bar = 3.14
    %]

The "WRAPPER" statement is also supported. The argument of "WRAPPER", however, must be string literals, because templates will be statically linked while compiling.

    [% WRAPPER "file.tt" %]
    Hello, world!
    [% END %]

    %%# with variable
    [% WRAPPER "file.tt" WITH title = "Foo!" %]
    Hello, world!
    [% END %]

The content will be set into "content", but you can specify its name with the "INTO" keyword.

    [% WRAPPER "foo.tt" INTO wrapped_content WITH title = "Foo!" %]
    ...
    [% END %]

This is a syntactic sugar to template cascading. Here is a counterpart of the example in Kolon.

    : macro my_content -> {
        Hello, world!
    : }
    : cascade "file.tx" { content => my_content() }

Note that the WRAPPER option (<http://template-toolkit.org/docs/manual/Config.html#section_WRAPPER>) in Template-Toolkit is not supported directly. Instead, you can emulate it with "header" and "footer" options as follows:

    my %vpath = (
        wrap_begin => '[% WRAPPER "base" %]',
        wrap_end => '[% END %]',

        base => 'Hello, [% content %] world!' . "\n",
        content => 'Xslate',
    );

    my $tx = Text::Xslate->new(
        syntax => 'TTerse',
        path => \%vpath,

        header => ['wrap_begin'],
        footer => ['wrap_end'],
    );

    print $tx->render('content'); # => Hello, Xslate world!;

  Macro blocks
Definition:

    [% MACRO foo BLOCK -%]
        This is a macro.
    [% END -%]

    [% MACRO add(a, b) BLOCK -%]
    [%  a + b -%]
    [% END -%]

Call:

    [% foo()     %]
    [% add(1, 2) %]

Unlike Template-Toolkit, calling macros requires parens ("()").

  Virtual methods
A few methods are supported in the Xslate core.

    %% a.size();
    %% a.join(", ");
    %% a.reverse();

    %% h.size();
    %% h.keys();
    %% h.values();
    %% h.kv();

However, there is a bridge mechanism that allows you to use external methods. For example, Text::Xslate::Bridge::TT2 provides the TT2 virtual methods for Xslate, which bridges Template::VMethods implementation.

    use Text::Xslate::Bridge::TT2;

    my $tx = Text::Xslate->new(
        syntax => 'TTerse',
        module => [qw(Text::Xslate::Bridge::TT2)],
    );

   print $tx->render_string('[% "foo".length() %]'); # => 3

See Text::Xslate::Bridge, or search for "Text::Xslate::Bridge::*" on CPAN.

  Misc.
CALL evaluates expressions, but does not print it.

    [% CALL expr %]

SET and assignments, although the use of them are strongly discouraged.

    [% SET var1 = expr1, var2 = expr2 %]
    [% var = expr %]

DEFAULT statements as a syntactic sugar to "SET var = var // expr":

    [% DEFAULT lang = "TTerse" %]

FILTER blocks to apply filters to text sections:

    [% FILTER html -%]
    Hello, <Xslate> world!
    [% END -%]

COMPATIBILITY
There are some differences between TTerse and Template-Toolkit.

•   "INCLUDE" of TTerse requires an expression for the file name, while that of Template-Toolkit allows a bare token:

        [% INCLUDE  foo.tt  # doesn't work! %]
        [% INCLUDE "foo.tt" # OK %]

•   "FOREACH item = list" is forbidden in TTerse. It must be "FOREACH item IN list".

•   TTerse does not support plugins (i.e. "USE" directive), but understands the "USE" keyword as an alias to "CALL", so you could use some simple plugins which do not depend on the context object of Template-Toolkit.

        use Template::Plugin::Math;
        use Template::Plugin::String;

        my $tt = Text::Xslate->new(...);

        mt %vars = (
            Math   => Template::Plugin::Math->new(),   # as a namespace
            String => Template::Plugin::String->new(), # as a prototype
        );
        print $tt->render_string(<<'T', \%vars);
        [% USE Math # does nothing actually, only for compatibility %]
        [% USE String %]
        [% Math.abs(-100)          # => 100 %]
        [% String.new("foo").upper # => FOO %]

•   The following directives are not supported: "INSERT", "PROCESS", "BLOCK" as a named blocks, "USE" (but see above), "PERL", "RAWPERL", "TRY", "THROW", "RETURN", "STOP", "CLEAR", "META", "TAGS", "DEBUG", and "VIEW".

    Some might be supported in a future.

SEE ALSO
Text::Xslate

Template (Template::Toolkit)

Template::Tiny

Text::Xslate::Bridge::TT2

Text::Xslate::Bridge::TT2Like

Text::Xslate::Bridge::Alloy